homescreens/folio: Halve the needed swipe distance for swipe detection

SwipeArea requires 10px to differentiate between taps and swipes. HomeScreenState uses a further 10px to differentiate between vertical and horizontal swipes. This MR combines the swipe detection together so that we only need 10px rather than 20px for gesture detection.

components/mobileshell/components/swipearea.cpp

@@ -284,7 +284,7 @@ void SwipeArea::handleMoveEvent(QPointerEvent *event, QPointF point)
         m_lastPos = point;
         m_stealMouse = true;
         setMoving(true);
-        Q_EMIT swipeStarted(m_startPos);
+        Q_EMIT swipeStarted(m_startPos, m_pressPos);
     }
 
     const QVector2D totalDelta = QVector2D(point - m_startPos);

components/mobileshell/components/swipearea.h

@@ -52,7 +52,7 @@ Q_SIGNALS:
     void pressedChanged();
 
     void swipeEnded();
-    void swipeStarted(QPointF point);
+    void swipeStarted(QPointF currentPoint, QPointF startPoint); // we let the user move a couple of pixels for swipe detection
 
     // deltaX, deltaY - amount moved since last swipeMove()
     // totalDeltaX, totalDeltaY - amount move since startedSwipe()

containments/homescreens/folio/homescreenstate.cpp

@@ -868,13 +868,17 @@ void HomeScreenState::cancelDelegateDrag()
     swipeEnded();
 }
 
-void HomeScreenState::swipeStarted()
+void HomeScreenState::swipeStarted(qreal deltaX, qreal deltaY)
 {
     if (m_swipeState != SwipeState::None) {
         return;
     }
 
     setSwipeState(SwipeState::DeterminingSwipeType);
+
+    // the user interaction has already moved a bit (for swipe detection),
+    // so we call the move event too.
+    swipeMoved(deltaX, deltaY, deltaX, deltaY);
 }
 
 void HomeScreenState::swipeEnded()

containments/homescreens/folio/homescreenstate.h

@@ -334,7 +334,7 @@ public Q_SLOTS:
     void cancelDelegateDrag();
 
     // from SwipeArea
-    void swipeStarted();
+    void swipeStarted(qreal deltaX, qreal deltaY);
     void swipeEnded();
     void swipeMoved(qreal totalDeltaX, qreal totalDeltaY, qreal deltaX, qreal deltaY);
 

containments/homescreens/folio/package/contents/ui/HomeScreen.qml

@@ -107,8 +107,10 @@ Item {
                 folio.HomeScreenState.swipeState === Folio.HomeScreenState.SwipingAppDrawerGrid ||
                 folio.HomeScreenState.viewState !== Folio.HomeScreenState.AppDrawerView)
 
-        onSwipeStarted: {
+        onSwipeStarted: (currentPos, startPos) => {
-            homeScreenState.swipeStarted();
+            const deltaX = currentPos.x - startPos.x;
+            const deltaY = currentPos.y - startPos.y;
+            homeScreenState.swipeStarted(deltaX, deltaY);
         }
         onSwipeEnded: {
             homeScreenState.swipeEnded();